(1) Field of the Invention
The present invention relates to a synchronous machine type treble frequency converter for converting a source power to a treble frequency power, i.e., to a power having a frequency three times that of the source.
(2) Description of the Prior Art
Two types of converters for converting a source power to a treble frequency power are known--a static-type frequency converter using semiconductor elements and a rotating machine type frequency converter having a motor-generator principle of operation.
The latter or rotating machine type is normally preferred in the construction field for use in powering small-power high-speed motors.
Conventional rotating machine type frequency converters generally use a motor operated from a power source to drive an alternating current generator. As such two machines, including cores, slip-rings and the like are required.
Synchronous machine-type frequency converters using a single core are also known. Since only a single machine is used, and since slip-rings or the like are not needed, such converters have the advantages of being compact in size, strong in construction and relatively maintenance-free. However, the relatively low efficiency of the known machines has made them undesirably heavy, resulting in higher manufacturing costs.